Microfluidic Systems for Marine Biotechnology 20.4 Microfluidic Systems for Other Marine Biotechnology Applications 521
Part C | 20.4
20.3.2 Microfluidics in Sea Pollutant
Detection
The rapid industrialization in chemical, biological, and
medical fields has resulted in the release of toxic
chemicals or potentially harmful pollutants into water
sources, including sea, groundwater, and rivers. These
pollutants are a great threat to human health. Therefore, a rapid and highly sensitive trace analysis of water
pollutants and minerals in marine and different water sources needs to be investigated according to the
stringent guidelines provided by different environmental protection agencies (EPA). Thus, the development
of a highly sensitive detection system for monitoring trace amounts of various pollutants and minerals
has become very important. A number of bulky and
conventional systems based on fluorescence, chromatographic, capillary electrophoresis, chemiluminescence,
and electrochemical detection methods were reported
previously. However, these bulky methods have many
limitations, such as a long sample preparation time,
a low detection limit, a lengthy measurement time, and
indirect measurement results.
Recently, there have been reports of various
portable microfluidic systems with extreme sensitivity
for pollutants and minerals, such as phosphate levels in treated wastewater [20.123] or fecal indicator in
coastal recreational water [20.124]. Another interesting approach uses whole-cell biosensor technology to
detect pollutants like herbicides and metal ions from
agricultural run-offs [20.125]. This technology presents
great advantages compared with conventional methodology, including portability, low cost, ease-to use, and
real-time monitoring. Unicellular microalgae have been
extensively exploited for evaluating toxicity of pollutants in aquatic ecosystems, due to their high sensitivity
to a number of pollutants and reproducibility [20.126].
Algae-based biosensors for water pollutant detection
have been reported by many groups [20.126–128].
For example, a microfluidic platform for water pollutant detection was developed to improve detection
sensitivity by integrating an algal fluorescence sensor [20.118]. This device consists of an organic light
emitting diode (OLED) and an organic photodetector
(OPD) integrated into a microfluidic chip. OLED and
OPD were used to detect algal fluorescence, as shown
in Fig. 20.7a. The presence of herbicides or metal ions
was detected with the diminution of the algae’s chlorophyll fluorescence. This device demonstrated a 10 times
higher sensitivity ( 10
8 M) towards herbicide than
values detected with a commercial fluorescence sensor, and 100 times higher compared to amperometric
algal biosensors. Another device developed by Beaton
et al. has demonstrated the possibility to measure with
high resolution in situ nitrate and nitrite [20.119]. The
circular poly (methyl methacrylate) (PMMA) microfluidic chip shown in Fig. 20.7b contains a fluidic manifold
that allows selection of standards, sample, and blank
solutions. The chip integrated a Griess assay and a spectrophotometric method for colorimetric nitrite analysis.
This LOC system demonstrates the potential of nutrient
analysis for inclusion in large-scale networks for ocean
pollution monitoring.
Another microfluidic device developed by Zheng
et al. (Fig. 20.7c) [20.120] has been reported for the
assessment of heavy metals in water, based on the measurement of motility of marine microalgae. The device
consists of a toxicant concentration gradient generator
where serial concentration gradients are generated by
diffusion, and a chemostatic module where cells are
seeded and migrate under different concentrations of
toxic heavy metals. It is known that marine microorganisms are often motile [20.129], and heavy metals,
such as, Cd and Cu, can directly inhibit cellular respiration processes that provide energy for motility [20.130,
131]. Therefore, a dose-response manner of Cd and Cu
on the motility of two marine bacteria was observed on
their microfluidic device.
20.4 Microfluidic Systems for Other Marine Biotechnology Applications
20.4.1 Synthesis of Marine Chemicals
Marine life forms are an important source of structurally diverse molecules with various biological properties, including toxic, pharmacological, and cosmetic
ones, as well as being important in biomedical research.
However, although nature provides structurally diverse
molecules with varying biological activities, it is not always possible to obtain the required quantities of the
desired molecule for research or commercialization;
either because the quantity of raw material is not sufficient to obtain the required amount of active product
of interest, or because active chemicals can only be isolated from endangered species protected by the Washington Convention (Convention on International Trade
in Endangered Species of Wild Fauna and Flora). This
Part C | 20.4
20.3.2 Microfluidics in Sea Pollutant
Detection
The rapid industrialization in chemical, biological, and
medical fields has resulted in the release of toxic
chemicals or potentially harmful pollutants into water
sources, including sea, groundwater, and rivers. These
pollutants are a great threat to human health. Therefore, a rapid and highly sensitive trace analysis of water
pollutants and minerals in marine and different water sources needs to be investigated according to the
stringent guidelines provided by different environmental protection agencies (EPA). Thus, the development
of a highly sensitive detection system for monitoring trace amounts of various pollutants and minerals
has become very important. A number of bulky and
conventional systems based on fluorescence, chromatographic, capillary electrophoresis, chemiluminescence,
and electrochemical detection methods were reported
previously. However, these bulky methods have many
limitations, such as a long sample preparation time,
a low detection limit, a lengthy measurement time, and
indirect measurement results.
Recently, there have been reports of various
portable microfluidic systems with extreme sensitivity
for pollutants and minerals, such as phosphate levels in treated wastewater [20.123] or fecal indicator in
coastal recreational water [20.124]. Another interesting approach uses whole-cell biosensor technology to
detect pollutants like herbicides and metal ions from
agricultural run-offs [20.125]. This technology presents
great advantages compared with conventional methodology, including portability, low cost, ease-to use, and
real-time monitoring. Unicellular microalgae have been
extensively exploited for evaluating toxicity of pollutants in aquatic ecosystems, due to their high sensitivity
to a number of pollutants and reproducibility [20.126].
Algae-based biosensors for water pollutant detection
have been reported by many groups [20.126–128].
For example, a microfluidic platform for water pollutant detection was developed to improve detection
sensitivity by integrating an algal fluorescence sensor [20.118]. This device consists of an organic light
emitting diode (OLED) and an organic photodetector
(OPD) integrated into a microfluidic chip. OLED and
OPD were used to detect algal fluorescence, as shown
in Fig. 20.7a. The presence of herbicides or metal ions
was detected with the diminution of the algae’s chlorophyll fluorescence. This device demonstrated a 10 times
higher sensitivity ( 10
8 M) towards herbicide than
values detected with a commercial fluorescence sensor, and 100 times higher compared to amperometric
algal biosensors. Another device developed by Beaton
et al. has demonstrated the possibility to measure with
high resolution in situ nitrate and nitrite [20.119]. The
circular poly (methyl methacrylate) (PMMA) microfluidic chip shown in Fig. 20.7b contains a fluidic manifold
that allows selection of standards, sample, and blank
solutions. The chip integrated a Griess assay and a spectrophotometric method for colorimetric nitrite analysis.
This LOC system demonstrates the potential of nutrient
analysis for inclusion in large-scale networks for ocean
pollution monitoring.
Another microfluidic device developed by Zheng
et al. (Fig. 20.7c) [20.120] has been reported for the
assessment of heavy metals in water, based on the measurement of motility of marine microalgae. The device
consists of a toxicant concentration gradient generator
where serial concentration gradients are generated by
diffusion, and a chemostatic module where cells are
seeded and migrate under different concentrations of
toxic heavy metals. It is known that marine microorganisms are often motile [20.129], and heavy metals,
such as, Cd and Cu, can directly inhibit cellular respiration processes that provide energy for motility [20.130,
131]. Therefore, a dose-response manner of Cd and Cu
on the motility of two marine bacteria was observed on
their microfluidic device.
20.4 Microfluidic Systems for Other Marine Biotechnology Applications
20.4.1 Synthesis of Marine Chemicals
Marine life forms are an important source of structurally diverse molecules with various biological properties, including toxic, pharmacological, and cosmetic
ones, as well as being important in biomedical research.
However, although nature provides structurally diverse
molecules with varying biological activities, it is not always possible to obtain the required quantities of the
desired molecule for research or commercialization;
either because the quantity of raw material is not sufficient to obtain the required amount of active product
of interest, or because active chemicals can only be isolated from endangered species protected by the Washington Convention (Convention on International Trade
in Endangered Species of Wild Fauna and Flora). This